Safety shutoff device for furnaces



April 2, 1946.-

M. s. czoLGosz SAFETY SHUT-OFF DEVI-[CE FOR FURNACES Filed May 21, 1945 al Patented Apr. 2, 1946 UNITED STATES .PATENT .QFFIcE SAFETY SHUTOFF DEVICE FOR FURNACES Michael S. Czolgosz, Gary, Ind., assigner of onehalf to Hyman Shanker, Gary, Ind.

Application May 21, 1945, Serial No. 594,910 (c1. 169-42) Claims.

The present invention relates to safety means for closing the dampers in a hot air furnace in the event that the heat becomes too great in the bonnet of the furnace. Hot air furnaces may become dangerous if the fire gets out of con-trol and the temperature in the bonnet rises to such a point that the air would start a fire either in the duct system or at the outlets thereof. Automatic draft controls embodying a thermostat have been used to overcome this danger te a certain extent. However, such devices are not completely reliable because the failure of the electric current will prevent them from functioning. Furthermore, there are many hot air furnaces used where the expensivethermostat and electric motor are not employed.

I am aware that several patented devices have been provided for the purpose of closing the draft door of a hot air furnace when it becomes overheated. Many of these devices are similar to the present device in that they depend upon melting a material having a low melting point to release some mechanical means, and thus permit the draft door to close. My invention, however, dif-A fers from these devices in that it provides a means whereby the melting fuse can be positioned at the proper place within the bonnet of the furnace to respond more readily to overheating, and can be replaced immediately without difficulty and without excessive expenseto the owner.

It is a purpose of the present invention to provide a safety device for hot air Vfurnaces wherein two control bars are mounted in face `to face relation to provide a channel throughout their lengths together with means pivotally"support ing each bar intermediate its ends for rotative movement independently of the other bar, and a fusible element in the channel of the bars holding them normally aligned, but allowing them to separate like the blades of a pair of. shears when the fusible element melts.

My invention contemplates a safety device of the above character which is readily mountable in the bonnet of a hot air furnace by providing an opening in the bonnet and clamping a mounting mechanism carrying the safety device to the opening. The opening must be situated so that the inner end of the safety device is positioned as nearly as possible over the hottest part of the furnace so that in the case of overheating, the safety device will respond promptly.

It is also a purpose of my invention to provide a safety device comprising two bars, one of which is connected to the damper and the other of which is connected to the damper regulating means, the bars being pivotally mounted on a common axis .betweentheir ends so that if they swing with respect to each other about the common pivot, the connection between the damper and the regulator will be varied as to length. In this combination it is also a purpose of my vin vention to secure a fusible element by providing a channel between the bars opened at the exterior of the furnace but closed within vthe vfurnace when the bars `are aligned.L This fusible element is maintained in position within the furnace bonnet by the tendency of the two bars to turn with respect to each other, and when the fusible element melts it releases the bars for such turning movement.

The nature and advantages of my invention will appear more fully from the following description and the accompanying drawing wherein a preferred form of the invention is disclosed. It should be understood, however, that the drawing and description are illustrative only, and that they should not be taken as limiting the invention except insofar as it is limited by the claims.

In the drawing:`

Figure l is a side view of a hot air furnace to which my invention has been applied. A portion of the bonnet of the furnace -is broken away to illustrate the mounting of my safety device.

Figure 2 is an enlarged view of the safety def vice and its mounting plates showing the open and closed position of--the safety device.

Figure 3 is a sectional view'taken on the line 3--3 of Figure 2, and

Figure 4 is an enlarged sectional viewtaken on the line 4 4 of Figure 2.

Referring now to the drawing, the'showing in Figure 1 is of an ordinary hot air furnace which comprises a fire box IIL-within a shell II, which terminates in an upper portion I2, which is normally termed the bonnet. The fire box has its air inlet opening at I3, which is controlled by a door I4. The outlet for `the products of'combustion from the fire box is shown as I5. The hot air used for heating purposes is drawn olf from the bonnet I2 through a main duct I6 and disa certain level and to release the flexible memmanner illustrated. The function of the safety device is to lengthen the member 'I1 and thus allow the "door I4 toc-lose in the event the temperature in the bonnet I2 reaches a dangerous height. The safety device I9 comprises two bars brings the twobars 20 and 2l into alignment 2U and 2I, preferably constructed of sheet metall Y' These twobars have ears 22 and 23 thereon.` The ear 22 which is on bar 20 is connected .tovthatr portion of the member I1 which extends down to the door I4. The ear 23 on thevb'arZ I is connected to the upwardly extending portion of the member I1. The two bars V and 2I have individual pivot pins 24 and ,25 respectively.- These `pivot pins are located intermediate the ends rofithe bars andare on Vthe same axis, so that the b ars can rotate with respect to each other like the blades of a pair of shears. jf Y y Y In order Vto mount the device I9 in the proper position, it is necessary to cut an opening 2t in the bonnet I2 through which the bars may extend intothe bonnet. VTwo mounting plates 21 and 28 are mounted on the'bonnet I2. One of the plates, that is plate 28,- has'two raised portions 29 and 3U providing bearings for the pins 24 and 2d. It will be .noted that the bars have circular projectionsf3l and 32 thereon, and the mounting plates 21 and 23 are cut out sothat they provide just sufficient clearance for the circular Vportion 3i and 32". This preventsleakage of air in any substantial quantity lthrough the bonnet wall. Y

The bars 20 and 2I'have opposed ,channels` 33 .and v34 extendinglengthwise thereof, so as to providejapassage from the ends of the'bars Vwhere the ears 22 and 23'are Vlocatedthroughoutthe length of the bars. The channels `33 and 34, however, terminate just short of the ,ends 35 of the bars. The bar 20 has a projection 35 bent` over ,f

top rovide a stop for vtheother kbar2I. Likewise the bar 2I hasa projetion31 bent. over to provide a stop for the bar 20. This makes it possible for the bars to lseparate in the direction indicated in Figure 2, but. they cannot Vbecausedtoseparate in the opposite direction.

',The kbars are locked together by. a fusible element 38 which is in the form-cfa small slug that can be dropped into the open end Vof the passage provided by the channels33 and 34 while the Ybars 2Q and 2l are `held in alignment. When the 'slug is adjacent the endg35 thebars can be released and the'tendency ofthe bars `to swing apart will hold-the slug in place. When'the :temperature in the bonnet :I2 reaches a danger point, the'slugv sult'is to lengthen the member vI1 an amountsuicient to close the door I4. v v

Whenever the `operator wants-.to restore the safetyV device to operative. condition,.he merely again, and drops a new slug 38 into the channel so as to lock the bars together.

Any low melting point metal may be used for the slug 38. The construction is such that immediately upon the slug melting to a point where the bars separate, the molten material of the slug runs out of the channels 33 and 34 so that these channels are not fouled, and new slugs can be inserted as often as is necessary. The shape of the slug and of the channel provided for it may of course be varied widely within the scope of my invention. Also more or less of the channel may be placed in either of the bars 2l! or 2I. Various other vminor modifications may obviously be made without departing from the scope of my invention.

.Y bars for mounting them on a furnace, said bars having longitudinally running channels in their engaging faces providing an elongated passage between the bars when they are aligned, and fusible means in said passage holding Vthe bars aligned, said bars having overlapping portions limiting separation of their opposed faces while they are aligned.

3. In a safety device ofthe character described, two bars having engaging faces, pivots on said bars for mounting them on `a furnace, said bars Vhaving longitudinally running channels in their engaging faces providing an elongated passage, open at one 'end and closed at the other, between the bars when they are aligned, and fusible means in said .passage-holding the bars aligned.

4. In a safety device of the character described, n .two bars having engaging faces, pivots on said bars for mounting them on a furnace, said bars having longitudinally running channels in 'their engaging faces, the channels opening to the edges of the bars at one end thereof and terminating short of the 'edges of the bars at the other end thereof, thereby providing an elongated passage vbetween the bars when they are aligned, and fusible means yin said passage holding the bars aligned. Y

5. Ina safety device'of the character described, two bars having engaging faces, pivots on said bars for mounting them on a furnace, said bars having longitudinally running channelsY in their Vengaging faces, the channels opening-tothe edges of the bars at onev end thereof, and terminating short of the edges of the Ybars, at the other end thereof, thereby providing an elongated'passage between 'the bars when they are aligned, and a removable fusible slug in said passage holding the bars aligned. W l

MICHAEL S. CZOLGOSZ. 

